Air atomizing spray bar



July 12, 1960 F. c. BAYER AIR ATOMIZING SPRAY BAR Filed Feb. 24, 1955 EFQ./

3 Sheets-Sheet 1 flQAA/AC 54%;?

July 12, 19 F. c. BAYER 2,944,388

* AIR ATOMIZING SPRAY BAR Filed Feb. 24,1955 5 Sheets-Sheet 2 fiA/vk C 452 rm July 12, 1960 F. c. BAYER 2,944,388

AIR ATOMIZING SPRAY BAR Filed Feb. 24, 1955 s SheerQs-Sheet s 15.22-5 .22 t Ur ffiAA/A (I. 54%? Bayer, Euclid,"i( )hi o, assignor to Thompson Ramo Wooldridgelne, a corporation of Ohio v Fiied Feb. 24, 1955, Ser. No. 490,330

This invention relates to improvements in afterburner assemblies for jet enginesor the like, and more particularly to means for supplying fuel'to the afterburnerassembly. Specifically, the invention deals with a novel air atomizing spray bar and its associated components which substantially improves afterburner efficiency. by improving the fuel distribution and atomization in the after burner chamber.

It is well known that the performance factors generally andthe thrust forces specifically generated by jet-type engines are greatly enhanced and improved by the' inclus'ion of an afterburner orthe like in the exhaust area or chamber of a jet-type mechanism. Heretofore", numeroustypes of afterburner constructions and assemblies have been developed in attempts to supply'the obvious demand therefor, and one conventional method of supplying fuel to the afterburner is by means-of simple spray bars which project radially intothe afterburner chamber.

L'Ihissimple'type of spray bar is supplied with fuel from a common manifold encircling theafterburner and comprises-a hollow tube closed at the end opposite the fuel supplyfitting and containing many small holes along its length through which fuel is discharged into the'afterburner. Essentially this type of spray bar is a fixedorifice composed of. many small orifices and exhibits'the typically parabolic pressure drop vs.' flow characteristic of a simple orifice. This characteristic readilyindic ated that at low weight rate of fuel, extremely poor operating conditions prevail. Because afterburner operation in current and projected jet enginesextends over a relatively wide fuel flow range, approximately 20-1, this simple fixed orifice type of .sp'ray 'bar is wholly inadequate and ineflicient.

.With a fuel flow range of 20-1, the pressure droprequired .to obtain: maximum fuel flow is 400 times that required for minimum. fuel flow; and in order to obtain satisfactory fuel distribution among the many spray bars around the afterburner,.: the pressure drop at minimum fuel fiow must besufiicien-tly high toIminimize the effect ofvelevation differences between theupper and lower spray bars. Thus, to obtain reasonable fuel distribution at minimum flow in an afterburner of about three feet invdiameter, a pressure drop of at least 4 psi. would be desirable; and to obtain a maximum fuel flow through such a spray bar, however, would require a pressure drop of 1600 p.s.i.which, in turn, would result inextreme fuel pump requirements and additional weight penalties to other fuel system components. It is readily understood that these additional requirements would tend to minimize the added efficiency obtained by the afterburner by effecting the overall eificiency of the engine itself. Moreover, the manufacturing cost of a jet engine' embodying these additional requirements would be materially increased. Another problem existing with this simple fixed orific type of spray bar was the failure of the spray bar to contribute towards satisfactory fuelatomization, since the fuel --'discharged from each orifice --on the'spray'bar-resembled the discharge of a stream of liquid from a childs water pistol. Any atomization and local distribution obtianed was dependent primarily on the air velocity and temperature in' the afterburner.

Additional difficulties experienced with this simple fixed orifice type spray bar include the prolonged draining and burning of fuel from the spray bars andmanifolding after the fuel supply valve was closed, and the cooking of fuel within the spray bar during and after the draining process with subsequent clogging of the small discharge orifices;

To overcome some of the shortcomings of a simple spray bar, the duplex type spray bars were developed, which included low flow and high flow portions, wherein fuel was supplied to only the-low flow portion during 'low fuel flow operation and to both portions during higher fuel flow operation. However, little if any improvement in fuel atomization was accomplished by the advent of the duplex spray bar. It was found that the operative region of poor fuel distribution due to elevation dilferences had only been displaced from the minimum fuel flow point to the region in Which the high flow portion of the duplex spray bar first becomes operative. Other difficulties experienced with the duplex type spray bar include: probably greater susceptibility to coking and clogging relative to the simple spray bar particularly in the case of the low flow portion which contained extremely, smalldischarge orifices, and the problem of-fuel drainage after shutdown was probably more acute as a result of the increased capacity of the duplex spray bars and the double fuel manifold; In addition, the duplex spray bar fuel system included an additional device in the form of an adequate flow divider which was neces sary to supply either the low flow manifold alone or both the low flow and the high flow manifolds with fuel as required. The sole advantage of the duplex spray bar over a simple spray bar was the obtaining of a more reasonable pressure drop requirement for wide flow range operation. Accordingly it'is an importantobject of this invention 'to obviate the aforementioned difiiculties heretofore experienced in afterburner spray bar assemblies in jet engines or-the like, and provide animproved spray bar arrangement which supplies an afterburner chamber with I atomized fuel, and which may be economically manufactured and easily installed in a jet engine without addi-ng any'appreciable weight to the jet engine.

Another object of this invention is to provide a spray bar assembly for' afterburners of jet engines or the like capable of operation by a supply of atomizing air which "is bled from the compressor discharge of the jet engine,

thereby eliminating the requirement for additional equipment in effecting efiicient operation thereof.

Still another object of the present invention resides in the provision of an improved afterburner spray bar arrangement for jet enginesorthe like which improves the fuel pressure drop vs. fuel flow rate characteristic for spray bars operable at lower fuel flow rates by simultaneously supplying fuel and atomizing air to thespray bars.

wherein maximum fuel atomization with a minimum of atomizing'air flow is accomplished.

' and provided with a plurality of discharge orifices, an inner, tube closed at one end disposed within the other tube andhaving a plurality of orifices concentrically aligned with said discharge orifices, whereby the space provided between the inner and outer tubes functions as a mixing chamber for the atomizing air and fuel which is subsequently dispersed as finely atomized fuel through the discharge orifices.

Still another object of this invention is to provide an afterburner spray bar adapted to protrude radially into an afterburner chamber, wherein the discharge orifices.

are spaced progressively close to one another with maximum spacing at the closed end of the spray bar.

A further object of this invention resides in the provision ofan afterburner spray. bar closed at one end and protrudin radially into an afterburner chamber, wherein discharge orifices are disposed along the spray bar andare sized progressively larger with the smaller orifices being located at the closed end of the spray bar.

Another object of this invention is to provide a spray bar unit for use in. afterburner chambers of jet enginesor the like, wherein the spray bar unit extends radially" into an afterbnrner chamber, and supporting means are provided to coextend with the spray bar unit in the afterburner chamber for addingstructural support to said unit.

Other objects, features and advantages of the'invention will be apparent from the following detailed-disclosures, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:

Figure 1 is a more or less schematic, longitudinal sectional elevational view of a jet type engine equipped with an after-burner assembly in accordance with the principles of the present invention;

Figure 2 is an enlarged sectional view of the spray bar in accordance with the present invention, taken substantially along line iiii of Figure 3;

Figure 3 is an enlarged elevational view ofthe spray bar in accordance with the present invention as shown in Figure 2 looking in the direction of line III-III there of;

Figure 4 is an enlarged bottom plan view of the spray bar looking in the direction of line IV--IV of Figure 3;

Figure 5 is a fragmentary elevational view similar to Figure}, but illustrating a modification of the invention, wherein the discharge orifices are spaced progressively further apart in the direction of the closed end; s

Figure 6 is a fragmentary elevational view similar to Figure 3, but illustrating yet another 'modificationof'thej invention, wherein the discharge orifices are equally spaced along the spray bar but sized progressively smaller towards the closed end; i s

Figure 7 is a graphic illustration of a family of characte ristic curves, for afterburner spray bar asemblies embodying the principles of the present invention, showing the fuel pressure drop vs. fuel flow rate for various specified atomizing air pressure drops;

Figure 8 is a graphicillustration ofa family of characteristic curves showing the atomozing air flow rate.

plotted against the fuel flow rate for varying atomizing air pressure drops in afterburner spray bar assemblies incorporating the principles of the present invention;

Figure 9' is an enlarged elevational view of a spray'bar.

7 51 unit similar to Figure 3, but illustrating a different form, wherein structural supports are employedalong a-portion of the spray bar which extends into an afterburner chamber of a jet engine or the like;

Figure 10 is a greatly enlarged elevational View of the spray bar unit of Figure 9, partly in section, and partly fragmentary;

Figure 11 is a top plan view of the spray bar unit of Figures 9 and 10; and

Figure 12 is a crosssectionalviewv of the sprayv bar unit of Figure 10; taken substantially along line XII--XII operated afterburner servesto inject additional fuel into:

the exhaust gases thereby burning out the surplusair or oxygen to raise the temperatures and pressures of the exhaust fumes which, in turn, increases the thrust forces of the jet engine andithe overall efficiency thereof.

Now referring to the drawings, there isschematically illustrated in Figure 1, a jet-type engine, generally designated by the numeral 10, having a housing or casing 11 of substantially tear-drop external configuration. housing 11, isv axially hollowed with anenlarged air entrance for intake at a. itsforward. or. front end as me dicated at 12, thereafter tapering to an exhaust nozzle! like rear end 13. Both thesintake end.12 and the exhaust end- 13; of the housingv 11, have substantially smooth curved edges 14 and 15, respectively, to minimizeany frictional resistance to air flow. A nose bell 16, of substantially semi-spherical configuration, is positioned partially within thehousing .11 at the intake end 12 and .coaxially therewith.

The. intake end 12 preferably. has aslightly flared mouth configuration internally of the housing 11, and together with the semi-spherical configurationiof the nose bell 16, gathers inlet air. and directsthe air into a conventional multistage axial flow compressor, indicated generally at 17; It isto be understood that a centrifugal compressor orvother suitable type of compressor may be used in place ofthe axial flow compressor 17.

compressor 17 toenter one or more combustion cans ,18,

forming a combustionvchamber, wherein fuel is supplied from main combustion fuel ejection nozzles. 19. The.

fuel may be supplied to the combustion nozzles. 19' in any-particular desired manner which herein is illustrated merely as a fuel line20, having a control valve 21 therein operatively connected to a .fuel control mechanism (not shown). In the combustion cans 18, of the combustion chamber, the fuel from nozzle 19 is ignited in the high pressure air from the compressorl17 so that theexhaust gases and flames create extremelyhigh'pressure and temperature exhaust conditions.

These extremely high temperature gases and'flames arev directed rearwardly through exhaust. nozzles, or ou'tleti ports 22 to drive a turbine 23. The gases passItu'rbine stator blades 24 or therlike fixedto housing 11 and thenare forcedagainst turbine rotor blades or thelike 25 which are mounted on a turbine rotorl 26. The turbine rotor 26 is drivingly connected to the compressor 17 by means of a shaft 27 which is coaxiallys supported 'byap:

propriateflbearings or the like (not shown) with the.

housing 11.

Followingthe turbine stage, the exhaust flames enter a propulsion afterburner or exhaust .cham: ber, generally indicated by the numeral 28, having a generally annularconical configuration definedby the substantially conical interior wall of housing ll as the external surface of the chamber, and by a nozzle correc h-- I Qr Pf 9 f is. shagtbe t The High' pressure and high temperature compressed air leaves the,

gases and.

high temperature and high pressure gases and flames are, of course, propulsion exhausted through the housing aperture or nozzle 13 at the trailing edge of the jet engine. It is to be understood that the particular jet engine illustrated in Figure 1 forms no part of the invention, and that the invention may be associated with and utilized with other types of jet engines. v

in accordance with the principles of the present invention, the afterburner assembly, generally designated by the numeral 30, as shown in Figure 1, is associated with the exhaust chamber of the jet engine near the trailing end of the toroidal portion of said chamber, although its location need not be exactly as indicated, as this would more or less depend upon the particular type ofjet engine. The afterburner assembly. 30 includes a plurality of spray bars 31 projecting radially into the afterburner chamber 28. 1

Atomizing air is supplied to the spray bar 31 through the air inlet 32, as shown in Figure 2, and is bled from the compressor 17 preferably at a point in the discharge thereof as indicated by thenumeral 33. The high temperature and high pressure air is carried through air sup- I ply line 34 and air'control valve or the like 35 to the air inlet 32 of the spray bar 31. The air control valve 35 is coupled in any convenient manner to an 'air control (not shown) as indicated. Although not shown, an 'air manifold or header may be suitably arranged to supply air to the plurality of spray bars in the afterburner chamber. I v a It should be noted that the air bled from the compressor discharge is not lost as-far as overall engine performanceis concerned, in contrast to air driven access'ories' from which the airis exhausted overboard.

The slight loss inefficiency resulting from .by-passing the small'quantity of atomizing airaround the turbine of the engine; is compensated for by an 'improvedf afterburner eificiency resulting from improved fuel'distribution and atomization, andultimately an increase in overall engine performance is obtained. v

The air inlet 32, in this instance, is provided with a threaded end for attachment to the air supply line 34 andis integral with the spray bar base'36. Communieating at right angles with the air passageway of the air inlet; 32 is an enlarged cylindrical bore 37. having an axial slot '38 (see Figure 3) open at its lower end. As the high temperature and high pressure air passes through the air inlet passageway it is then directed at right angles through the base 36 and guided into an air tube 39 having for a short distance a cylindrical-portion 39a which merges into an elongated elliptical or oval shaped portion 39b terminating in a closed end 390. A plurality of equally spaced relatively small air orifices 40 are pro ,vided along both broad facesof the elliptical portion 39b of air tube 39. Carried at the inner end of air tube 39 is-an outwardly flared flange portion 41 suitablyshaped Y to seat on a more-or less centrally apertured cone shaped portion of base 36 and to be rigidly held thereto by comple'm'entary'faces of a sleeve 37a;

Sleeve 31a isapertured at 42 to receive'in sealing engagementa fuel inlet member 43 which carries a threaded portion to be suitably connected with fuel supply line 44.

The fuel supply through line 44 is controlled by valve 45a which is operatively connected to suitable fuelcontrol (not shown); A fuel restriction orifice 45 is carried atthe' inner end of thefu'el inlet 43. Although not shown, a fuel-manifold or 'header' may-be provided to supply the fuel to the plurality of spray bars, as was explained in regards to the air inlet'32 outer tube 46 encloses air tube39 and is similarlyshaped having a cylindrical portion 46a'at its inner end and-an outer oval or elliptical shaped elongated portion 46b terminating in a closed end46c. Carried at the inner :end of, the tube. 46 and'supporting it with respect to;the. base .36 is an outwardly flared flange portion 47 having a beveled faceseatingpu a like beveled face of '9 46 against the base 36 is removably held to said base by fastening means, such as cap screws 49 (see Figure 4). As shown in Figure 4, apertures 50 adjacent the terminal end of plate 48 are provided to enable the spray bar 31 to be attached to the afterburner or exhaust shell.

A plurality of discharge orifices 51 are equally spaced along the broad faces of the elliptical portion 46b of tube 46 and are concentrically aligned with the air orifices 40 of the inner tube 39, but are of a larger size.

As seen in Figure 2, it is noted that the outer tube 46 is spaced from the inner air tube 39 providing therebetween a mixing chamber 52 within which the fuel is received from the fuel restriction orifice 45 to be subsequently mixed with the atomizing air discharged through air orifices 40, thereby ultimately providing an atomized fuel which is dispersed in afinely atomized spray of fuel into the afterburner chamber 28.

Since the source of atomizing air in a jet engine is at the compressor discharge, the static pressure is always sufiiciently higher than that existing in the afterburner.

The air pressure drop available for atomization may vary inatypical engine from a minimum of 10 p.s.i. to 200 p.s.i. over the range of flight conditions.

Typical performance characteristics of the spray bar in accordance with the instant invention are illustrated- -by the families of curves of Figure 7. -In this figure fuel pressure drop is plotted on the vertical axis, in arbitrary units, against weight rate offnel flow on the h0rizontal -axis, in arbitrary units. The individual curves are plotted at select atomizing air pressure drops also measured in" arbitrary unitsunder preselected conditions. -With no air flow (atomizing air pressure drop equal 7 to zero), a normal parabolic pressure drop vsffuel flow .characteristic results. This normally parabolic pressure pressure drops ranging from 10 to 180 units 1n the same vs. fuel flow characteristic is the one whichnormally obtains with simple spray bars, which are not provided with atomizing air inlets thereto. Examination of the curve at the right of Fig. 7 readily illustrates that very poor low-fuel flow rate control is available.

On the other hand, by adding atomizing air to the 'afterbur ner spray bars, the fuel pressure drop vs. fuel flow characteristics-are greatly improved, particularly in the low fuel flow rate region of operation, and hence, betterlow fuel flow rate control is available. For example, it will be noted that the characteristic curves, identified by atomizing air pressure drops equal to 10, 20, 40, 6( 80, and 180, open in the direction of increasing weight rateoffuel flow while the characteristic curve for no atomizing air pressure drop opens in the direction of increasing fuel pressure drop. And it is noted that the no atomizing air pressure drop curve allows for practically no control while the curves for atomizing air pressure drops permit a high degree of fuel flow rate in the low fuel flow region, particularly below the fuel flow of 200.

The family of curves of Figure 8 illustrate the typical air flow characteristics of the spray bar in accordance with the instant invention, wherein atomizing air flow vs. fuel flow characteristics with weight rate of atomizing air flow is plotted increasingly along the vertical axis and the Weight rate of fuel flow plotted increasingly along the horizontal axis. The units for these coordinates have been arbitrarily selected and the air temperature has been maintained constant for all the curves.

The individual curves represent individual atomizing air manner asunits selected for the individual curves of Figure. 7. Y

The sizes of the fuel restriction 45, the air orifices 40,

and the discharge orifices 51 are selected to obtain a pressure in themixing: chamber 52 less than the atomizingair supply at any given operating condition, an optimum fuel pressure drop vs. flow characteristic, and maximum fuel atomization with the minimum of atomizing air flow.

Since the pressure in the mixing chamber 52. is always less than the atomizing air supply pressure, air flow through the spray bar 31 is then always available to assist in atomizing the fuel, and any possible back fiow of fuel into the air supply line 34-is prevented.

By the proper selection of the ratio of discharge orifice to air orificearea in combination with the fuel restriction, the slope of the curve of fuel pressure vs. flow is considerably greater in the low flow region than that obtainable with a simple fixed orifice type ofspray bar which is not supplied with atomizing air, as shown in Figure 7. As a-result of the greater slope of the pressure'drop vs. flow curve, the effect of an equivalent 1 p.s.i. elevation head dilference between the upper and lower spray bar in the'afterburner is reduced considerably and improved-fuel distribution around the afterburner is obtained, particularly in the low flow region.

Fuel atomization is achieved as a result of the relative velocity of the air and fuel in the mixture flowing through the discharge orifices. Although the pressure drop experienced-by the air and fuel in the mixing chamber while flowing through the discharge orifices is identical, the velocity of the air in themixture is considerably greater than that of the fuel as a result of the lower-air density, and in addition,"the ensuing expansion'of the airinthe mixture further aids atomization. The result is a finely atomized spray of fuel from the discharge orifices.

Inactual practice it would probably be desirable to:

space the discharge orifices 51 progressively closer to one another with maximum spacing at the closedend of the spray bar 3i, as shown by spray bar 31a inFigure' 5,. since the eross-sectional'area of the afterburner served by each unit length of the spray bar increases along the radius ofthe afterburner;

An alternative discharge orifice arrangement would be to provide progressively larger air and discharge orifices from the closed end of the spray bar toward the supply a plug 63a closing the outer free end of the tube 63, and a plurality of air orifices 63b longitudinally spaced along diametrically opposite areas of the bar 63. An outer tube or hollow bar as extends from the base 60, surrounding the inner bar 63, and is provided with a plug 64a closing the outer freeend of the tube 64 and a plurality of-discharge orifices 64b spaced along diametrically opposite regions of the bar 64. The discharge orifices 54b are preferably larger than the air orifices 6317, as seen in Figure l2, and are in concentric alignment therewith. The outer end of the inner hollow bar 63 is loosely guided within the plug 54a of the outer bar 64. An annular mixing chamber 65 is defined by the outer Wall of inner tube 63 and the inner wall of outer tube 64, and the fuel inlet 62 communicates with mixing chamber at the base end thereof.

The major difference between the embodiment illustrated in Figures 9-12 and the embodiment ofFigures 2-4 resides in the provision of a pair of supporting arms 66,- 66,- best shown in Figures 9, l0 and 12, which extend outwardiy from the base 6% in partial surrounding engagement with the outer tube or bar 64 for adding structural support to the. relatively weaker tube members thereby guarding against undue deflection or fracture ofsaid tube members which would render them inefricient or useless,

The supporting arms 66 take the form or, arcuate seg: mer ts in cross-section, and are, longitudinally tapered with thelargerlends being adjacent the, base 60; Although they support arms 66 are-shown as not extending, completely to-theendofthe outer tube 64, in some cases, it may be desirableto-proyide arms having the same length as the thevarious parts of the spray bar unit are preferably brazed or welded together, thereby providing a completely brazed or welded spraybar assembly, although other suitable means for securing the various parts together may be employed.

Thespray bar unit of Figures 9-12 maybe secured-to.

an afterburnesWall-in the same manner as theerjnbodiment of Figures 2-4 shown in Figure 1. Likewisethe function of the modified spray bar unit is substantially the samefas the spray-bar unit 31.

It is to be;und e rsto0d that the spray bar unit; of Figures 2-4 mayalsobe' equipped with support arms for aiding they support thereofwithin an; afterburner chamber as illus-,.

trated -j by the modified embodiment of Figures 9-12. Hence, it is seenthatapplicant has provided a means for j structurally -supporting;a spray bar-unit-within an afterburner chamber or other chamber of a jet-engine-or the like.

It will be understood that modifications and variations may be effected without departing from the scope of-the noyelconcepts-of the present invention.

'1 claim as my invention: 1: In a-jet engine having a source ofalr under pressure,

a source of fuel, and a combustion chamber, the improve:v ment ofa spray bar in said combustion chamber having an inside, tube; connected with said source of-air and equipped with air ejection orifices at spaced intervals along the length thereof, first means controlling-flow from said-air source to said; air ejection orifices, a second tubesurrounding said first-mentioned tubeconnectedWith-said;

source of fuel and equipped with orifices along the length thereof for dischargingair atomized fuel into the 'combustion=chamber,,and second means controllingflow from said fuelsource to the orifices in'said, second tube, said; second tube providing a'mixing chamber around the first? mentioned tube receiving air from the air ejection nozzles for admixing with the fuel-in the second tube,.,

2;, In a ,turbojet engine having an air compressor, a source o-ffuel, and an afterburner chamber, the improve,-

ment of a spray barin said 'afterburnerchamberhaving; an inner apertured tube connected with said compressor; and anouter' apertured tube surrounding said innerp tube, in spaced; relation therefrom and connected with said fuel 7 source, valve means for controllingflow of compressedair; irom'the compressor to said inner tube, valvetmeans for controlling flow from said fuel source to said outer tube,

and the space between said inner and outer tubes provid-,

ing a mixing chamber for atomizing fuel with air to discharge a controlled spray of fuel into the afterburner chamber'th-rou'ghout awide flow range.

3 A spray barunit for jet engines, and the-like, which; comprises a first elongated hollow tubular member closed .3 at one end and havinga fuel inlet at the opposite end, a

second; elongated tubular member in said first member having an air inlet at one end and closed at the other end;

in said first member, said first and second members provid:

ing a mixing .chamberztherebetween, orifices, along the lengths of said members, first and second meansrespec tively controlling fuel and air flow tosaidfuel and airinlets the orifices insaid-second member being smaller than theorifices in said-first member, and'jsaid first and secondmembers being imperviousv from the inletsthereof;

for a considerable distance to the first orifices therein.

4. An afterburner spraysbar unit for jet engines, or the like, adapted to be mounte'd onthe housingof an engine and protrude radially inward into the afterburner chamben.

of the engine which comprises a supporting base having an air inlet and a fuel inlet, fuel andair conduits respectively feeding fuel and air to said fuel and air inlets, a valve in each conduit controlling the rates of fuel and air flow to said fuel and air inlets anelongated first hollow bar extending from said base in communication with the fuel inlet of the base and closed at its free end, said first bar being ovate along most of'its length, said first bar having a plurality of discharge orifices axially spaced along the length thereof, a second elongated hollow bar extending from said base within said first bar and closed at its free end, said second bar communicating with the air inlet of the base and freely received within said first bar to provide a chamber between the bars, a plurality of orifices in said second bar axially aligned with the orifices of said first bar, and said supporting base having amounting flange to secure the unit in position on the engine.

7 5. A jet engine having a housing defining an afterburner chamber, a plurality of individual spray bars for supplying an atomized fuel to said afterburner chamber, each spray bar being mounted at the outer end thereof on said housing and extending radially into the afterbumer chamber, each spray bar including an outer elongated generally oval shaped tube protruding radially inward from the housing wallinto the after burner chamber and terminating in a closed free radial inner end, said oval shaped tube being oriented in the afterburner chamber to present its broad face in alignmentwiththe longitudinal axis of said chamber, a fuel inlet at the outer end of said tube, said tubehaving a series of discharge orifices along each broad face thereof spaced pro- "free end, an inner elongated air tube in said oval shaped tube in slightly spaced generally coaxial relation therewith, an air inlet at the outer end of said inner tube in communication with the interior of the tube, said inner tube having air orifices along the length thereof concentrically aligned with said discharge orifices of said outer oval shaped tube, and said oval shaped outer tube coaoting with said inner tube to define therebetween an annular mixing chamber whereby air from the air inlet discharges through said air orifices along the length of said inner tube into fuel from the fuel inlet along the length of said outer oval shaped tube to mix with the fuel and disperse a finely atomized air-fuel mixture through the discharge orifices along the length of the broad faces of said oval shaped tube into said afterburner chamber, and means for regulating the flow of fuel and air respectively to said fuel and air inlets for controlling the air-fuel ratio and the degree of atomization of the fuel. t

6. A spray bar unit for jet engines or the like which comprises, a supporting base, a pair of hollow bars mounted on and extending from 'said base, each bar closed at the free end thereof, one of said bars smaller in cross-section'and surrounded by the otherbar, an annu lar chamber defined by said bars, an air inlet in said base communicating with said smaller bar, a fuel inlet in said base communicating with said chamber, a plurality of orifices along the length of each bar, and arm meanson said base extending from said base and partially sur-' rounding said outerbar to provide structural support thereto. 7

7. A spray bar unit for jet engines or the like which 2 comprises a supporting base, a first inlet in said base for receiving atomizing air, a second inlet in said base for receiving fuel, a first elongated hollow bar extending from said base in communication with said first inlet and terminating in a closed end, a second elongated hollow bar extending from said base and terminating in a closed end, said second bar surrounding said first bar, an annular mixing chamber defined by said first bar and said second bar, said chamber communicating with said second inlet, a plurality of orifices in each bar, and at least one arm member extending from said base and engaging a portion of the outer wall of said second bar along the length thereof for providing support thereto.

8. A spray bar unit for jet engines or the like which comprises a supporting base, a first inlet in said base for receiving atomizin-g air, a second inlet in said base for receiving fuel, a first elongated hollow bar extending from said base in communication with said first inlet and terminating in a closed end, a second elongated hollow bar extending from said base and terminating in a closed end, said second bar surrounding said first bar, an annular mixing chamber defined by said first bar and said second bar, said chamber communicating with said second inlet, a plurality of orifices in each bar, and a plurality of supporting members extending from said base and in partial surrounding engagement with said second bar except in the region of the orifices, but terminating short of the bar end.

9. Aspraybar' unit for an afterburner chamber in a jet engine orthe like which comprises, a supporting base adapted to be securedto an afterburner wall, a first hollow bar extending from said base to project into said chamber, a first inlet in said base for supplying atomizing air to said bar, a plurality of air orifices along the a bar, a, second hollow .bar extending from said base in co-extending and surrounding relationship to said first bar, a plurality of discharge orifices in said second bar in aligned relationship with said orifices of said first bar, an annular mixing chamber defined by the inner wall area of said second bar and the outer wall area of said first bar, a second inlet in said base communicating with sid mixing chamber for supplying fuel thereto, and a pair of supporting arms extending from said base and in surrounding engagement with said second bar except in the longitudinal region of the discharge orifices.

References Cited in the file of this patent UNITED STATES PATENTS 1,702,784 Koplin Feb. 19, 1929 1,952,236 Clawson Mar. 27, 1934 2,595,999 Way et al. May 6, 1952 2,635,425 Thorpe et a1. Apr. 21, 1953 2,657,532 Reid et al. Nov. 3, 1953 2,699,969 Ter Stege et al Jan. 18, 1955 2,745,251 Schirmer May 15, 1956 2,771,743 Lovesey Nov. 27, 1956 2,780,061 Clarke et a1. Feb. 5, 1957 2,780,915 Karen Feb. 12, 1957 2,861,424 Jurisich' Nov. 25, 1958 FOREIGN'PATENTS' 1,085,458 France July, 28, 1954 588,847 Great Britain a June 4, 1957' 648,699 a Great Britain; Jan. 10, 1951 666,944 Great Britain Feb. 20, 1952 690,941

Great Britain Apr. 29, 1953 

